Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Rust pathogen Puccinia jaceae is established on yellow starthistle (Centaurea solstitialis) in Oregon.

Abstract

Puccinia jaceae var. solstitialis was released under APHIS permit 11 times at 7 sites in Oregon (USA) between May 2008 and April 2011 for biological control of the invasive weed yellow starthistle (Centaurea solstitialis). This paper presents evidence for the establishment and spread of P. jaceae in Oregon, which was not apparent for at least 3 years after release. Disease on C. solstitialis is a likely result of the original release made at the Myrtle Creek site, although absolute proof is impossible. It is noteworthy that P. jaceae did not establish in Northern California at locations near Oregon. This is thought to be the first confirmation of permanent establishment and spread of P. jaceae on C. solstitialis outside of California where, after inoculations at 176 sites in 40 counties, it has become permanently established only in Sonoma Co., near San Pablo Bay. It is too early to determine if the disease is affecting population density of C. solstitialis in the vicinity of the release site, but such is now possible after this discovery. Careful examination and monitoring of this and the other release sites in Oregon is planned.